DOI: 10.1039/D0GC00949K
Page 9 of 11
Green Chemistry
aqueous system. The precipitated catalyst was washed with ether (3 × 5.0
(m, 2 H, -S-CH2-CH2-CH3), 1.59-1.52 (m, 2 H, -S-CH2-CH2-CH3), 0.95-
0.89 (m, 3 H, -S-CH2-CH2-CH3).
mL), dried at room temperature in vacuum, and finally recharged with
fresh substrate for the next catalytic cycle. Supernatant separated from
reaction system was extracted with dichloromethane (3 × 0.5 mL).
5 Combined organic phase was dried with anhydrous Na2SO4 and
concentrated in vacuum. Further purification of the residue by
chromatography on silica gel (Acros, 40–60 μm, 60 Å, eluent: petroleum
ether/ethyl acetate = 5/1 (v/v)) afforded the desired chiral adducts. All
60
(S)-3-(4-Chlorobenzylthio)-1,3-diphenylpropan-1-one (6): Yield: 93%,
determined by isolated yield after column chromatography. Ee value:
95%, determined by HPLC (iPrOH/n-hexane = 20:80 (v/v)), flow rate =
1.0 mL·min-1, 25 °C, λ = 254 nm, major enantiomer tS = 8.51 min; minor
1
enantiomer tR = 6.42 min. H NMR (CDCl3, 500 MHz): δ (ppm): 7.89-
65 7.42 (m, 5 H, Ph-CO-CH2-), 7.40-7.35 (m, 4 H, Cl-Ph-CH2-), 7.28-7.14
(m, 5 H, Ph-CH-S-), 4.17-4.12 (m, 1 H, -S-CH-Ph), 3.59-3.51 (m, 2 H, -
S-CH2-Ph), 3.51-3.44 (m, 2 H, CH-CH2-CO-).
1
products of 1-7 were identified by H NMR spectra. Their enantiomeric
10 excess (ee) values were determined by high performance liquid
chromatography (HPLC) analysis using the Daicel Chiralpak AD
columns. Detailed NMR spectra and HPLC analysis for the products of 1-
7 were available in the ESI.†
(S)-3-(4-Chlorobenzylthio)-3-(4-methoxyphenyl)-1-phenylpropan-1-one
(7): Yield: 90%, determined by isolated yield after column
70 chromatography. Ee value: 96%, determined by HPLC (iPrOH/n-hexane
= 3:97 (v/v)), flow rate = 1.0 mL·min-1, 25 °C, λ = 254 nm, major
(S)-3-(Propylthio)-1,3-diphenylpropan-1-one
(1):
Yield:
95%,
1
15 determined by isolated yield after column chromatography. Ee value:
96%, determined by HPLC (iPrOH/n-hexane = 10:90 (v/v)), flow rate =
1.0 mL·min-1, 25 °C, λ = 254 nm, major enantiomer tS = 5.75 min, minor
enantiomer tS = 20.15 min, minor enantiomer tR = 17.48 min. H NMR
(CDCl3, 500 MHz): δ (ppm): 7.33-7.17 (m, 13 H, Cl-Ph-CH2-, CH3O-Ph-
CH-, and Ph-CO-CH2-), 4.17-4.15 (m, 1 H, CH-CH2-CO-), 4.14-4.13 (m,
75 2 H, Cl-Ph-CH2-S-), 3.60 (s, 3 H, CH3O-Ph-CH-), 2.99-2.91 (m, 2 H, CH-
CH2-CO-).
1
enantiomer tR = 4.82 min. H NMR (CDCl3, 500 MHz): δ (ppm): 7.95-
7.46 (m, 5 H, Ph-CO-CH2-), 7.45-7.15 (m, 5 H, Ph-CH-S-), 4.59-4.56 (m,
20 1 H, CH-CH2-CO-), 3.57-3.56 (d, 2 H, CH-CH2-CO-), 2.41-2.23 (m, 2 H,
-S-CH2-CH2-), 1.60-1.49 (m, 2 H, S-CH2-CH2-CH3), 0.94-0.91 (m, 3 H,
S-CH2-CH2-CH3).
(S)-4-(4-Chlorobenzylthio)pentan-2-one (8): Yield: 94%, determined
by isolated yield after column chromatography. Ee value: >99%,
determined by HPLC (iPrOH/n-hexane = 10:90 (v/v)), flow rate = 1.0
80 mL·min-1, 25 °C, λ = 254 nm, major enantiomer tS = 6.07 min, minor
enantiomer tR = 4.99 min. 1H NMR (CDCl3, 500 MHz): δ (ppm): 1H NMR
(CDCl3, 500 MHz): δ (ppm): 7.33-7.27 (m, 4 H, Cl-Ph-CH2-), 3.75-3.74
(m, 2 H, Cl-Ph-CH2-), 3.20-3.13 (m, 1 H, -S-CH-CH3), 2.73-2.64 (m, 2 H,
CH-CH2-CO-), 2.14 (s, 3 H, -CO-CH3), 1.64-1.52 (m, 3 H, CH3-CH-
85 CH2).
(S)-4-(Propylthio)-4-phenylbutan-2-one (2): Yield: 96%, determined
by isolated yield after column chromatography. Ee value: 99%,
25 determined by HPLC (iPrOH/n-hexane = 20:80 (v/v)), flow rate = 1.0
mL·min-1, 25 °C, λ = 254 nm, major enantiomer tS = 6.12 min, minor
1
enantiomer tR = 4.74 min. H NMR (CDCl3, 500 MHz): δ (ppm): 7.55-
7.31 (m, 5 H, Ph-CH-S-), 4.49-4.46 (m, 1 H, CH-CH2-CO-), 3.25-3.24 (d,
2 H, CH-CH2-CO-), 2.39-2.23 (m, 2 H, -S-CH2-CH2-CH3), 1.57-1.53 (m,
30 2 H, -S-CH2-CH2-CH3), 1.36 (s, 3 H, -CO-CH3), 0.96-0.91 (m, 3 H, -S-
CH2-CH2-CH3).
(S)-3-(4-Chlorophenylthio)-1,3-diphenylpropan-1-one (9): Yield: 92%,
determined by isolated yield after column chromatography. Ee value:
98%, determined by HPLC (iPrOH/n-hexane = 20: 80 (v/v)), flow rate =
1.0 mL·min-1, 25 °C, λ = 254 nm, major enantiomer tS = 10.34 min, minor
90 enantiomer tR = 8.34 min. 1H NMR (CDCl3, 500 MHz): δ (ppm): 7.44-
7.41 (m, 5 H, Ph-CO-CH2-), 7.32-7.29 (m, 9 H, Ph-CH-S- and Cl-Ph-S-),
2.05-2.03 (m, 1 H, CH-CH2-CO-), 1.60-1.58 (d, 2 H, CH-CH2-CO-).
(S)-3-(Propylthio)-3-(4-methoxyphenyl)-1-phenylpropan-1-one
(3):
Yield: 92%, determined by isolated yield after column chromatography.
Ee value: 98%, determined by HPLC (iPrOH/n-hexane = 20:80 (v/v)),
35 flow rate = 1.0 mL·min-1, 25 °C, λ = 254 nm, major enantiomer tS = 12.32
1
min; minor enantiomer tR = 10.08 min. H NMR (CDCl3, 500 MHz): δ
(ppm): 7.94-7.43 (m, 5 H, Ph-CO-CH2-), 7.39-6.82 (m, 4 H, CH3O-Ph-
CH-), 4.56-4.53 (m, 1 H, CH-CH2-CO-), 3.81 (s, 3 H, CH3O-Ph-CH-),
3.57-3.48 (d, 2 H, CH-CH2-CO-), 2.38-2.23 (m, 2 H, -S-CH2-CH2-CH3),
40 1.60-1.49 (m, 2 H, -S-CH2-CH2-CH3), 0.97-0.88 (m, 3 H, -S-CH2-CH2-
CH3).
Acknowledgements
The authors are grateful for the financial support provided by
95 the National Natural Science Foundation of China (21676078,
21476069), the Natural Science Foundation of Hunan Province
for Distinguished Young Scholar (2016JJ1013), Scientific
Research Fund of Hunan Provincial Education Department
(19A323), and Science and Technology Planning Project of
100 Hunan Province (2018TP1017). We also thank Dr. Mingjie
Zhang, Wenqin Fu, and Ziqiang Xiao for their helpful
discussions.
(S)-4-(Propylthio)-4-(4-methoxyphenyl) butan-2-one (4): Yield: 95%,
determined by isolated yield after column chromatography. Ee value:
90%, determined by HPLC (iPrOH/n-hexane = 10:90 (v/v)), flow rate =
45 1.0 mL·min-1, 25 °C, λ = 254 nm, major enantiomer tS = 11.04 min, minor
1
enantiomer tR = 8.11 min. H NMR (CDCl3, 500 MHz): δ (ppm): 7.75-
6.91 (m, 4 H, CH3O-Ph-CH-), 4.40-4.30 (m, 1 H, CH-CH2-CO-), 3.92-
3.87 (d, 2 H, CH-CH2-CO-), 2.64 (s, 3 H, CH3O-Ph-CH-), 2.28-2.23 (m, 2
H, -S-CH2-CH2-CH3), 2.09-2.01 (m, 2 H, -S-CH2-CH2-CH3), 1.40 (s, 3 H,
50 -CO-CH3), 0.92-0.85 (m, 2 H, -S-CH2-CH2-CH3).
Notes and references
[1] a) D. Enders, K. Lüttgen and A. A. Narine, Synthesis, 2007, 7, 959; b)
105
110
X. Wang, Q. Hua, Y. Cheng, Q. Yang, J. Chen and W. Xiao, Angew.
Chem. Int. Ed., 2010, 49, 8379; c) M. N. Grayson and K. N. Houk, J.
Am. Chem. Soc., 2016, 138, 9041; d) Y. Li, S. Zhu and Q. Zhou, Org.
Lett., 2019, 21, 9391.
[2] a) N. K. Rana, S. Selvakumar and V. K. Singh, J. Org. Chem., 2010,
75, 2089; b) L. Dai, S. Wang and F. Chen, Adv. Synth. Catal., 2010,
352, 2137; c) J. Guo and M. W. Wong, J. Org. Chem., 2017, 82, 4362.
[3] E. Emori, T. Arai, H. Sasai and M. Shibasaki, J. Am. Chem. Soc.,
1998, 120, 4043.
(S)-3-(Propylthio)-3-(4-nitrophenyl)-1-phenylpropan-1-one (5): Yield:
10%, determined by isolated yield after column chromatography. Ee
value: 89%, determined by HPLC (iPrOH/n-hexane = 30:70 (v/v)), flow
rate = 1.0 mL·min-1, 25 °C, λ = 254 nm, major enantiomer tS = 11.78 min,
1
55 minor enantiomer tR = 10.01 min. H NMR (CDCl3, 500 MHz): δ (ppm):
8.20-7.81 (m, 4 H, NO2-Ph-CH-), 7.75-7.46 (m, 5 H, Ph-CO-CH2-), 4.79-
4.50 (m, 1 H, CH-CH2-CO-), 3.78-3.44 (d, 2 H, CH-CH2-CO-), 2.50-2.18
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